Pressurized circulating fluidized bed reactor combined cycle power generation system

Abstract

A combined cycle power generation system incorporates a carbonizer and a pressurized fluidized bed reactor for the generation of fuel gas and flue gases, respectively. A combustor is provided for the combustion of the fuel gas in the presence of the flue gases to produce hot gases. The hot gases are passed through a gas turbine where the gases expand and cool while performing work in the generation of electrical power. The exhaust gases from the gas turbine are passed though a heat recovery unit for the production of steam. The exhaust gases are then combined with air and passed to the pressurized fluidized bed reactor to provide excess secondary gas to aid in driving the gas turbine.

What is claimed is: 
     
       1. A method of generating power using a combined cycle system comprising the following steps: producing fuel gas having solid fuel particles entrained therein;   separating said fuel gas from said solid fuel particles;   burning said solid fuel particles with air in a reactor to produce flue gases having solid particles entrained therein;   separating said flue gases from said latter solid particles;   passing said latter solid particles to a heat exchanger for cooling a portion of said latter solid particles;   passing said cooled portion of said particles and the remaining portion of said particles from said heat exchanger back to said reactor, the ratio of said cooled portion of said particles to said remaining portion of said particles being adjustable to control the temperature of said reactor;   combusting said fuel gas in the presence of said flue gases in a combustor to produce gaseous products of combustion;   passing said gaseous products of combustion from said combustor to a gas turbine to drive said turbine and generate electrical energy;   utilizing heat from the exhaust gases from said turbine to produce steam; and   passing said steam to a steam turbine to drive said steam turbine and produce electrical energy.   
     
     
       2. The method of claim 1 wherein said reactor has an upper portion and a lower portion, said upper portion having a greater cross sectional area than said lower portion, and said method further comprises: apportioning the cooled exhaust gases from said gas turbine into a first portion and a second portion;   passing said first portion of said cooled exhaust gases to an exhaust stack;   compressing said second portion of said cooled exhaust gases;   forming secondary gases by injecting air into said compressed exhaust gases; and   injecting said secondary gases into said upper reactor portion so that said secondary gas completes combustion.   
     
     
       3. The method of claim 2 wherein the step of separating said fuel gas from said solid fuel particles includes the following steps: substantially separating said fuel gas from said solid fuel particles;   substantially filtering said substantially separated fuel gas; and   wherein the step of separating said flue gases from said solid particles produced in said reactor includes the following steps:   substantially separating said flue gases from said solid particles produced in said reactor; and   substantially filtering said substantially separated flue gases.   
     
     
       4. The method of claim 3 wherein the step of producing is performed in a carbonizer, and said method further comprises the step of controlling the residence time of said solid fuel particles in said carbonizer by draining said solid fuel particles from said carbonizer and passing said solid fuel particles to said reactor. 
     
     
       5. The method of claim 1 wherein said flue gases contain oxygen and wherein said step of combusting is in the presence of said oxygen. 
     
     
       6. The method of claim 1 wherein said particles are cooled in said heat exchanger by the steps of apportioning said solid particles in said heat exchanger into a first portion and a second portion, fiuidizing said particles in said first and second portions, and cooling said first portion. 
     
     
       7. A combined cycle power generation system comprising: a carbonizer for producing fuel gas having solid fuel particles entrained therein;   first separating means for substantially separating said fuel gas from said solid fuel particles passing from said carbonizer;   a pressurized fluidized bed reactor for receiving said solid fuel particles from said first separating means, said reactor burning said solid fuel particles with air to produce flue gases having solid particles entrained therein;   second separating means for substantially separating said flue gases from said solid particles passing from said reactor;   a heat exchanger for receiving the separated solid particles from said second separating means and for cooling a portion of said latter particles; means for passing said cooled portion of said particles and the remaining portion of said particles from said heat exchanger back to said reactor, the ratio of said cooled portion of said particles to said remaining portion of said particles being adjustable to control the temperature of said reactor;   a combustor for combusting said fuel gas in the presence of said flue gases to produce gaseous products of combustion;   a first turbine for receiving and utilizing said gaseous products of combustion to produce torque for the generation of electrical energy;   means connected to said first turbine for receiving hot exhaust gases from said first turbine and for utilizing said hot exhaust gases to produce steam; and   a second turbine for receiving and utilizing said steam to produce torque for the generation of electrical energy.   
     
     
       8. The system of claim 7 wherein said reactor has an upper portion and a lower portion, said upper portion having a greater cross sectional area than said lower portion, and said system further comprises: an exhaust stack;   an exhaust gas compressor;   means for passing a portion of said exhaust gases from said first turbine to said exhaust gas compressor for compressing said exhaust gases, and for passing another portion of said exhaust gases from said first turbine to said exhaust stack;   means for producing secondary gases by injecting air into said compressed exhaust gases; and   means for injecting said secondary gases into said upper reactor portion so that said secondary gas completes combustion.   
     
     
       9. The system of claim 8 wherein said first separating means includes: a first cyclone separator for receiving from said carbonizer, and substantially separating, said fuel gas and said solid fuel particles;   a first ceramic cross-flow filter for receiving from said first cyclone separator, and filtering, said substantially separated fuel gas, passing thereby substantially pure fuel gas to said combustor and passing substantially separated and filtered solid fuel particles to said lower portion of said reactor; and   wherein said second separating means includes:   a second cyclone separator for receiving from said reactor, and substantially separating, said flue gases and said solid particles; and   a second ceramic cross-flow filter for receiving from said second cyclone separator, and filtering, said substantially separated flue gases, passing thereby substantially pure flue gases to said combustor and passing substantially separated and filtered solid particles to said heat exchanger.   
     
     
       10. The system of claim 9 further comprising means for draining said solid fuel particles from said heat exchanger and passing said drained solid fuel particles to said reactor to control the residence time of said solid fuel particles in said reactor. 
     
     
       11. The system of claim 7 wherein said heat exchanger comprises a vessel having an air distribution plate arranged to form a plenum in a lower portion of said heat for consistency and a chamber in an upper portion of said heat exchanger, said chamber having a partition wall extending upwardly from said plate to form first and second portions of said chamber for receiving said solid particles from said second separating means, said plenum adapted to receive air to fiuidize said particles, and means for cooling particles in said first portion of said chamber to fore said cooled portion of said particles.